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The effects of rhenium (Re) and high-angle grain boundaries upon the elemental distribution and microstructure of as-cast Ni-based single-crystal superalloy blades are investigated herein. The addition of Re reduces the coarsening of the γ dendrite and γ' phases. Further, the degree of partitioning of the element Al in the γ' phase decreases with Re addition, while that of the elements Ta, Ti, Ni, and Mo increases. The addition of Re greatly decreases the concentration gradient, and greatly increases the diffusion distance, of the alloying elements in the region close to the γ/γ' phase boundary. As the grain boundary angle increases from 35° to 45°, a Re -enriched σ phase is directly precipitated from the γ' phase at the grain boundary. In addition, both the amount of σ phase and the concentration of Re in that phase increase with increasing grain boundary angle. • Interactive effect of Re addition on elements distribution are studied. • Re changes elements diffusion from short- to long-distance at γ/γ' phase boundary. • Effect of HAGs on elements distribution and microstructure formation is studied. • Increasing Re is observed at grain boundary with increasing HAGs' angle. • With increasing HAGs' angle, increasing σ phases are precipitated from γ' phase. [ABSTRACT FROM AUTHOR]

We examine the stock market reaction to the SEC announcement to permanently exempt non-accelerated filers from compliance with Section 404(b) of the Sarbanes–Oxley Act. Mandatory compliance with auditor attestation under Section 404(b) is highly controversial. Using a sample of non-accelerated issuers for 2006–2011, we find a negative market reaction to the November 4, 2009 exemption announcement. However, most of the negative returns accrue to non-accelerated filers that do not voluntarily comply with Section 404(b), suggesting that auditor attestation enhances firm value. The use of a Big 4 auditor, strong analyst following, and superior internal controls over financial reporting (ICFR) are associated with positive/less negative market responses. Voluntary compliers with Section 404(b) are more likely to have a Big 4 auditor, stronger analyst coverage, effective ICFR, stronger firm performance and lower information asymmetry. Our results are consistent with firms using voluntary compliance with SOX 404(b) as a signal of superior operating performance and ICFR quality to overcome information asymmetry and therefore mitigate the negative valuation impact of the permanent exemption from auditor attestation. [ABSTRACT FROM AUTHOR]